Novadessus viracocha, a new genus and species of Bidessini Sharp from Peru (Coleoptera, Adephaga, Dytiscidae, Hydroporinae)

Abstract Novadessus viracocha gen. n. and sp. n. is described from Peru. The genus distinctly is characterized by having the following combination: (1) a transverse occipital line absent on the head; (2) the anterior clypeal margin not modified; (3) a pair of basal pronotal striae present; (4) the basal elytral stria absent; (5) the elytral sutural stria absent; (6) the elytron without longitudinal carinae; (7) the epipleuron without a transverse carina at the humeral angle; (8) the lateral lobes of the male aedeagus two-segmented; (9) the overall habitus elongate and oval, with lateral pronotal and elytral margins discontinuous; (10) without distinct denticles along the posterior margins of the abdominal sternites; (11) the male genitalia (both median lobe and lateral lobes) bilaterally symmetrical; and (12) the metatrochanter small relative to the metafemur, approximately 0.6 × the length of the metafemur. The genus is diagnostically similar to Fontidessus Miller and Spangler and Neobidessodes Hendrich and Balke, but is superficially more similar to Liodessus Guignot. The habitus and male genitalia are illustrated, and a distribution map is provided.


Introduction
The diving beetle tribe Bidessini Sharp has provided large numbers of new species and genera over the past few years, especially in the Neotropical region (Miller 2016;Miller and Garcia 2011;Miller and Montano 2014;Miller and Short 2015;Miller and Spangler 2008). The few characters that typically characterize bidessine genera come in numerous combinations making diagnoses complex and relationships difficult to establish. Bidessini is currently the largest clade of diving beetles, and the group promises to continue to grow as new diversity is discovered.
A new species was discovered among legacy specimens from the US National Collection that could not be assigned to an existing genus. Therefore, the goal of this project is to describe a new genus and new species of Bidessini from Peru.
Images. Illustrations were made using a drawing tube on a Zeiss Discovery V8 dissecting scope. Sketches were first done in pencil then scanned, placed into an Adobe Illustrator artboard and "inked" digitally using vector lines.
Diagnosis. Novadessus is characterized by the following combination: (1) a transverse occipital line absent on the head; (2) the anterior clypeal margin not modified; (3) a pair of basal pronotal striae present; (4) the basal elytral stria absent; (5) the elytral sutural stria absent; (6) the elytron without longitudinal carinae; (7) the epipleuron without a transverse carina at the humeral angle; (8) the lateral lobes of the male aedeagus two-segmented; (9) the overall habitus elongate and oval, with lateral pronotal and elytral margins discontinuous; (10) without distinct denticles along the posterior margins of the abdominal sternites; (11) the male genitalia (both median lobe and lateral lobes) bilaterally symmetrical; and (12) the metatrochanter small relative to the metafemur, approximately 0.6 × the length of the metafemur.
The genus is relatively similar in appearance and overall shape of the male genitalia to Liodessus Guignot, a rather generalized group of Bidessini species. However, Novadessus is missing both the transverse occipital line across the back of the head and the basal elytral striae, each of which is characteristic of Liodessus. In Miller and Bergsten (2016) the genus keys out to couplet 13 which separates Fontidessus Miller and Spangler and Neobidessodes Hendrich and Balke, neither of which is a convincing fit. Fontidessus, though Neotropical like Novadessus, have a characteristic ventral sclerite on the male median lobe and very large metatrochanters, neither of which are present in Novadessus. Neobidessodes have a rather different body shape (elongate oval with a continuous lateral body line), are Australian, and do not appear to be similar in any other particular way to Novadessus. Spanglerodessus Miller and García and Amarodytes Régimbart (both Neotropical) each also have the combination of absence of an occipital line, presence of pronotal striae and absence of elytral striae, but the first is very broad and broadly rounded laterally with a broad pronotal bead and the second has the pronotal striae generally short, curved and located somewhat laterally. In addition, each group is superficially quite distinct from Novadessus in many other less discrete characters such as body shape, overall coloration, surface sculpture, etc. Even so, the relationships of Novadessus to these other taxa, and to other Bidessini genera in general, is unknown and needs investigation.
Etymology. This genus is named Novadessus from the Latin word, novus, meaning "new" and dessus, a common root for genera in the Bidessini.

Diagnosis.
Monotypic. The male median lobe in lateral aspect is expanded medially and evenly curved to a narrowed, apically narrowly rounded apex (Fig. 2). The coloration is overall brownish.
Coloration. Head, including appendages, evenly brown. Pronotum brown, somewhat darker along anterior and posterior margins. Elytron brown, lighter brown laterally. Ventral surfaces brown, legs, head and epipleuron lighter brown than thoracic and abdominal sternites.
Sculpture and structure. Head surface finely but distinctly microreticulate and micropunctate; without occipital line or modifications to evenly rounded clypeal margin. Pronotum surface smooth and shiny with few micropunctures scattered across surface; lateral margins broadly rounded with bead narrow; broadest anteriorly, narrowed posteriorly; lateral striae distinctive, extending anteriorly more than half distance across pronotum. Elytron smooth and shiny with fine, distinctive punctures distributed evenly; lateral margins subparallel anteriorly, narrowed to posteriorly pointed apex; basal and sutural striae absent. Prosternum moderately broad; prosternal process nar-row, apically sharply pointed, medially rounded. Mesoventrite and metacoxal surfaces smooth and shiny with few, scattered fine punctures; metacoxal lines anteriorly somewhat divergent. Abdominal surfaces smooth and shiny with few scattered punctures. Metatrochanter small, ventrally rounded, not strongly offset from line of metafemur; metafemur slender, unmodified.
Variation. Specimens vary somewhat in intensity of coloration, but are otherwise similar.
Etymology. This species is named viracocha after the Inca creator god. Distribution. The species is known from two series. The type series bears label data indicating it is from "Vic. of Shishmay." Shishmay is a small town in the Andes of Peru (Fig. 5). The other series has label data indicating "Vic. San Domingo," in Huanuco, Peru. This second locality could not be located. Habitat. The type series was collected from "highland lakes." Nothing else is known of the habitat of Novadessus viracocha.